Radiation-induced defects in GaN bulk grown by halide vapor phase epitaxy

Defects induced by electron irradiation in thick free-standing GaN layers grown by halide vapor phase epitaxy were studied by deep level transient spectroscopy. In as-grown materials, six electron traps, labeled D2 (EC–0.24 eV), D3 (EC–0.60 eV), D4 (EC–0.69 eV), D5 (EC–0.96 eV), D7 (EC–1.19 eV), and D8, were observed. After 2 MeV electron irradiation at a fluence of 1 × 1014 cm−2, three deep electron traps, labeled D1 (EC–0.12 eV), D5I (EC–0.89 eV), and D6 (EC–1.14 eV), were detected. The trap D1 has previously been reported and considered as being related to the nitrogen vacancy. From the annealing behavior and a high introduction rate, the D5I and D6 centers are suggested to be related to primary intrinsic defects.